Anybody have a tag for this?

[darklyndsea]

So, I was looking back over my already-posted fic and realized that there's a trope that I really want a name for but don't have one to tag with. Basically, it's where one character at some point starts living the life of another canon character. Normally, it's done with crossovers but I've seen it done via time travel too. Does anybody have a good tag for that?